Hitherto, for example, as seats for first class and business class cabins, seats provided in aircrafts are known to adopt a seat structure which can be changed selectively between a configuration in which a backrest is positioned upright for passengers to be seated and a configuration in which the backrest is reclined in a horizontal state to enable the seat to be used as a bed.
In many cases, these types of the seat structure are configured as a seat module, i.e., seat unit, in which a seat capable of being reclined is arranged in a space surrounded by wall-like partition members (refer, for example, to Japanese Patent Literatures 1 and 2).